1. Field of the Invention
The present invention relates to a sheet ejecting device, an image forming system, and a sheet ejecting method. Particularly, the present invention relates to a sheet ejecting device that blows a wind to a carried sheet-like recording medium, such as paper, recording paper, transfer paper, and an OHP sheet, (hereinafter, referred to as “sheet”) when it is aligned and stacked; an image forming system that includes the sheet ejecting device and an image forming apparatus, such as a copier, a printer, a facsimile machine, or a digital multi-function machine; and a sheet ejecting method that is performed by the ejecting device.
2. Description of the Related Art
Conventional sheet processing devices are known and widely used that perform various types of post processing, such as alignment, stapling, folding and binding, and that are thus referred to as sheet post processing devices. In recent years, requirements for such sheet post processing devices to deal with sheets have greatly increased. Particularly, regarding color image forming apparatuses, the portion of printing performed on coated sheets (hereinafter, “coated paper”) that enable clear images for leaflets, flyers, etc. is increasing. Normally, coated paper has the following characteristics:
1) high surface smoothness,
2) high coherence between sheets, and
3) low Clark hardness.
These characteristics may lower the stackability of coated paper.
A technique to improve stackability is known in which an air layer is formed by using fans in order to stack an ejected sheet in a normal position. Regarding such a technique, the invention disclosed in Japanese Laid-open Patent Publication No. 2003-002512 is known.
The invention is characterized by a sheet ejecting device that includes a sheet ejection table that is provided with side fences on its both sides for regulating both side edges of a sheet that is ejected from a printing unit; blower fans; air outlets from which air sent from the blower fans is blown onto the back side of the sheet that falls into the bottom of the ejection table; an environmental temperature checking unit that checks the environmental temperature; and a blower controller that changes the air blown from the blower fans according to the checked environmental temperature.
The blowing of air by using fans that is disclosed in Japanese Laid-open Patent Publication No. 2003-002512 can prevent buckling in the transfer direction. However, because ejected sheets are electrically charged, ejected sheets may cohere to each other due to static electricity.
An object of the invention is to prevent ejected sheets from cohering to one another and to have good accuracy in alignment of the stacked sheets.